The present invention relates to an actuating device with an electromotive rotary drive and more particularly to the actuating element, which can be driven rotatably about an axis of rotation between a first end position and a second end position and further acted upon out of the first end position by a spring.
In actuating devices of this type, it is known to operate the actuating element by means of the electromotive rotary drive counter to the force of the spring and over the entire actuating travel between the first and second end positions. During operation of the actuating device, a permanent operation of the electromotive actuating drive is also required. A permanent supply of current and therefore a permanent expenditure of energy is also consequently necessary. Since, in this case, the activating electronics of the actuating drive is also operated permanently, the load on these electronics, particularly as a result of heating, is high and necessitates higher-grade electrical and electronic components, with the result that the activation electronics are costly.
If the actuating device serves for regulating the operation of a further device, such as, for example, for regulating the stream of a cooling liquid in a coolant circuit of the internal combustion engine for a motor vehicle, it is necessary that, in the event of a failure of the actuating device, a sufficient cooling liquid stream continues to be maintained, so that the internal combustion engine can be operated further, at least in an emergency running mode.
This is not possible with known actuating devices, since, in the event of failure, the actuating element is moved into the second end position by the spring. This means that the cooling circuit is either completely shut off or completely open, the both of which do not correspond to the cooling requirements.